The present invention relates to a fine-feed adjusting device for a sewing machine, and more particularly to a device for fine adjustments of feed pitches of left-hand and right-hand stitchings, used especially in a buttonhole stitching.
In conventional pattern stitchings formed by the sewing machines, discrepancies have occurred in feed pitches between a forward feed and a backward feed due to types of fabrics, threads, pressing pressure and other factors, and the patterns have often appeared to be awkward. Especially in the buttonhole stitchings, if the left-hand stitching is on the forward feed and the right-hand side stitching is on the backward feed, and if the feed pitches of each feed do not coincide with each other, the stitchings become non-satisfactory. Therefore, a fine adjustment of the feed pitch has been necessary. There have been many proposals where machine operators handle appropriate adjusting members during the running of the sewing machine in order to finely adjust the feed pitches. However, the sewing machine, in which a pulse motor is a power source which actuates a feed adjusting device, is complicated in structure and expensive, and is also not durable.